Chemical fingerprinting of hydrothermal ore deposit systems

热液矿床系统的化学指纹图谱

• 批准号: RGPIN-2015-05782
• 负责人: Kontak, Daniel
• 金额: $ 1.6万
• 依托单位: Laurentian University of Sudbury
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=613744
• 关键词: Chemical; fingerprinting; hydrothermal; ore; deposit

The research undertaken in this program will address truly fundamental questions about how important types of gold deposits form. Until now, geologists have understood the fluids that carry and deposit gold in both metamorphic and magmatic gold deposits to be ‘low-salinity aqueous-carbonic fluids’ (H2O-CO2±CH4). This description is extremely simple, grossly oversimplifies the complexity of the ore fluids that have been proven to be involved in specific examples of each of the deposit types, and ignores subtleties of fluid composition that may be critical to ore formation. More problematically, this description encourages the assumption that these ore deposit types are similar, even though their fundamental tectonic settings are clearly entirely different. Is it really possible that the ore-depositing fluids in strikingly different geologic settings are so similar and so simple? Answering this question will help geologists understand the fundamental processes behind the formation of gold deposits, a significant part of the Canadian economy for past century, much better, and will also help mineral exploration companies focus their work and their expenditures more efficiently. The work proposed will compare two well known gold terranes in Canada of vastly different age, geological setting and gold endowment: one dominated by metamorphic deposits (Meguma; Nova Scotia) and one having mixed metamorphic -magmatic deposits (Abitibi; Ontario). The methods employed will be a novel combination of analytical approaches that has not hitherto been used on such deposits (or any others). Gold-bearing and associated non-gold-bearing minerals form at the same time and contain information about where the gold came from and the conditions under which it was deposited. Importantly, quartz veins hosting the gold traps minute volumes of the mineralising fluid, called fluid inclusions, which can be sampled and analysed using both common and highly specialised methods. These methods permit quantifying the fluid chemistry and a direct means to assess its origin, which has never been done before, and will then provide a basis to reassess the genetic models for these gold deposits. The associated sulphide minerals (e.g. arsenopyrite) also record the fluid chemistry much like rings in a growing tree. Elemental mapping of these sulphides allow one to reconstruct the fluid history and indirectly assess the origin of gold and its time of entrapment. The combination of the methods employed in two very contrasting settings will provide for the very first time absolute data on the fluid chemistry in gold mineralized systems. These data will form the basis for reassessing the genetic models used to explore for these precious resources. The methodology employed will also provide a foundation for similar studies to be applied to other hydrothermal ore-forming systems in order to address similar outstanding issues.

该计划中进行的研究将解决有关黄金存款的重要类型的真正基本问题。到目前为止，地质学家已经了解了在变质和岩浆黄金沉积物中携带和沉积黄金的流体为“低含量水溶液 - 谐波液”（H2O-CO2±CH4）。该描述非常简单，非常过分简化的矿石流体的复杂性已被证明与每种沉积物类型的特定示例有关，并且忽略了可能对矿石形成至关重要的流体组成的微妙之处。更有问题的是，该描述鼓励以下假设：这些矿石存款类型相似，即使它们的基本构造环境显然完全不同。在截然不同的地质环境中，矿石销售的流体真的有可能是如此相似且如此简单吗？回答这个问题将有助于地质学家了解形成黄金存款背后的基本过程，这是加拿大经济的重要部分，在过去的一个世纪中，也更好，也将帮助矿产勘探公司更加有效地集中于他们的工作和支出。 提出的工作将比较加拿大的两个众所周知的黄金地块，具有截然不同的年龄，地质环境和金捐赠：一种以变质沉积物（Meguma; Nova Scotia）为主导，而一个具有混合变质 - 巨型质量的沉积物（Abitibi; Ontario）。所采用的方法将是迄今未在此类沉积物（或其他任何一种）上使用的分析方法的新型组合。同时形成了含金和相关的非金属矿物质，并包含有关黄金来自何处及其沉积条件的信息。重要的是，矿物质液体的石英静脉含有矿物质流体的微量量，称为流体夹杂物，可以使用常见和高度专业的方法对其进行采样和分析。这些方法允许量化流体化学和评估其起源的直接手段，这是以前从未做过的，然后将提供基础，以重新评估这些黄金沉积物的遗传模型。相关的硫化物矿物质（例如，砷氧化石）也像生长树上的环一样记录了流体化学反应。这些硫化物的元素映射使人们可以重建流体病史，并间接评估黄金的起源及其捕获时间。 在两个非常相比的设置中进行的方法的组合将提供有关金矿化系统中流体化学的绝对数据。这些数据将构成重新评估用于探索这些宝贵资源的遗传模型的基础。该方法采用的方法还将为类似研究提供基础，以应用于其他水热矿石形成系统，以解决类似的杰出问题。